Wednesday, July 30, 2008

Paleontologists in 2005 hailed research that in fact showed that soft, pliable tissues had been recovered from dissolved dinosaur bones; most important finding that would substantially widen the known range of preserved biomolecules.

But new research challenges that finding and suggests that the supposed recovered dinosaur tissue is in reality biofilm – or slime. "I supposed that preserved soft tissues had been found, however I had to change my opinion," said Thomas Kaye, an associate researcher at the Burke Museum of Natural History and Culture at the University of Washington. "You must go where the science leads, and the science directs me to believe that this is bacterial biofilm."

The original research, published in Science magazine, claimed the finding of blood vessels and what appeared to be entire cells inside fossil bone of a Tyrannosaurus rex. The scientists had dissolved the bone in acid, leaving behind the blood vessel- and cell-like structures. But in a paper published July 30 in PloS ONE, a magazine of the open-access Public Library of Science, Kaye and his co-authors challenge that what was truly inside the T. rex bone was slimy biofilm created by bacteria that coated the voids once occupied by blood vessels and cells.

The scientists also dissolved bone in acid, as had been done earlier, and found the same soft tissue structures. They conducted a comparison by means of infrared mass spectroscopy and determined the structures were more strongly related to modern biofilm than modern collagen, extracellular proteins connected with bone. Carbon dating placed the origin at around 1960.

By an electron microscope, the researchers saw coatings on the vascular canal walls that contained gas bubbles, which they related with the presence of methane-producing bacteria. Also they examined what looked like tiny cracks within the vascular canals and found that they were in fact small troughs, or channels. Study at high magnification discovered the channels had rounded bottoms and bridged each other, indicating they were in nature created, likely by bacteria moving in a very thick solution.